To know the units of t span used in ode45 command

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I am using ODE45 command to solve 8 ordinary differential equations. My doubt is if im specifying tspan=[0 1000] , what will be the units of time like is it in seconds, minutes, hours?
code:
tspan=[0 1000];
yo=[1;2;3;4;5;6;7;8;9];
[tsol,ysol]=ode45(@filename,tspan,yo];
  2 Comments
James Tursa
James Tursa on 22 Jul 2021
The units of tspan is dictated by how you formulate your differential equation in the function handle. ode45( ) doesn't assume or know anything about units.

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Accepted Answer

Yongjian Feng
Yongjian Feng on 22 Jul 2021
You can type this in the matlab command line window:
help ode45
to get help for ode45 function.
The first input argument is a function handler. This is the function that tells you what t means. In other words, whatever unit of t is used in the function handler, it is also used in the tspan.
Does it make sense?
Thanks,
Yongjian

More Answers (1)

Steven Lord
Steven Lord on 22 Jul 2021
There is no unit inherent to the t variable used by ode45. Just implement your ODE function correctly for your time units.
If you're solving a physics problem and using standard gravity you should formulate it in seconds.
If you were modeling a predator-prey system using the Lotka-Volterra equations then your time units would probably be years.

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